Integrated receptor modeling and trajectory analysis for source apportionment of heavy metals in settled dust fall...

Dust fall enriched with heavy metals poses critical risks to both environmental and human health, particularly in arid and semi-arid regions of the Middle East. This study investigates the distribution and source apportionment of 11 heavy metals (Fe, Mg, Mn, Cu, Zn, Ni, Pb, Cr, As, Cd, Ag) in dust fall samples collected over 1 year from three cities in western Iran: Sanandaj, Khorramabad, and Andimeshk. Using receptor modeling techniques-positive matrix factorization (PMF), UNMIX, and principal component analysis (PCA)-major contributing sources were identified. Furthermore, backward trajectory modeling using the HYSPLIT model was applied to assess transboundary dust transport patterns. The results showed that both crustal sources (characterized by Fe, Mg, and Mn) and anthropogenic sources (represented by As, Ag, Pb, Cd, Zn, Cr, Cu, and Ni) were dominant contributors in the study area. PMF identified five key emission sources, while UNMIX and PCA yielded four principal factors. The HYSPLIT analysis confirmed that a significant portion of dust events originated from southeastern Iraq. The integrated modeling approach demonstrated strong agreement among methods and allowed for refined source attribution. Given the elevated levels of toxic metals such as Pb, Cd, and Cr, this study emphasizes the importance of including health risk assessment in future research. The findings offer valuable insights for local air pollution control and underscore the need for regional collaboration in mitigating transboundary air pollution impacts.